US2245537A

US2245537A - Recovery of phosphatides

Info

Publication number: US2245537A
Application number: US248356A
Authority: US
Inventors: Benjamin H Thurman
Original assignee: REFINING Inc
Current assignee: REFINING Inc
Priority date: 1938-12-29
Filing date: 1938-12-29
Publication date: 1941-06-10
Anticipated expiration: 1958-06-10

Description

June 10,v 1941# B. H. THURMAN y y REoovERYvoF PHosPHATIDEs Filed Dec. 29, 1938 Patented June l0, 1941 RECOVERY F PBOSPHATIDES Benjamin n. Thurman, Bmnxviue, N. Y., assignor to Refining, Inc., Reno, Nev., a corporation of Nevada Application December 29,1938, Serial No. 248,356 I Claims.

This invention relates to the recovery of phosphatides from vegetable oils, and more particularly to a process in which the oils are treated to remove -certain impurities before the phosphatides are separated therefrom in order to produce a purer phosphatide product.

Vegetable oils such as cottonseed oil, soya bean oil, corn oil, rapeseed oil, sesame oil, etc., in their crude state, usually' contain substantial portions of phosphatides. This is particularly true of ypressed oils, although solvent extracted oils may also contain recoverable phosphatides. In general, hot pressed oils contain the greater amount and, therefore, constitute an excellent source of vegetable phosphatides, although oils produced by other methods frequently contain sufcien-t phosphatides to render the recovery thereof economically feasible. Vegetable oils `containing phosphatides almost invariably also contain substantial proportions of other -material-s such as proteins, resins and carbohydrates which are separated to a large extent along with the phosphatides as gums in so-called degumming processes. These other materials constitute impurities in the phosphatidic material, so that a relatively impure phosphatidic material is produced by such processes. The separation of these other materials from the phosphatides after they have been all separated together in degumming operations usually requires repeated washing and solvent treating steps. It has been found, however, that a large portion of these other materials may be separated from the crude oil by selectively precipitating the same Without precipitating substantial quantities of phosphatides and then the oil containing the phospha- -tides -can be further treated to separate a relatively pure phosphatidic material. The present invention is advantageously carried out as a continuous process in a closed system.

It is, therefore, an object of the present invention to provide an improved process of obtaining relatively pure phosphatidlc material from vegetable oils.

Another object of the invention is to provide a process of obtaining relatively pure phosphatidic material from vegetable oils in which impurities ordinarily separated with the phosphatides are removed from the oil prior to the separation of the phosphatides.

A further object of the invention. is to provide a process of recovering phosphatides from vegetable oils in which the oil is treated to remove impurities other than phosphatides and (Cl. 26o-403) then treated to remove relatively pure phosphatides. s

A still further object of the invention is to provide a continuous process of recovering relatively pure phosphatides from vegetable oils.

Other objects and advantages of the invention will appear in the following description, given in connection with the attached drawing, which is a` schematic diagram of an apparatus capable ofcarrying out a continuous process in accordance with the present invention.

Referring more particularly to the drawing, crude vegetable oil may be withdrawn from a source of supply shown as a tank I 0 by means of a pump II and delivered through a heat exchange device I2 to a mixer I3. The heat exchange device I2 may include a coil I4 through `which the oil is passed, which coil is surrounded by a casing I5 through which any desired heat- .a continuous centrifugal separator 2l.

ing medium maybe circulated. A stream of precipitating reagent, which may be termed a protein precipitating agent, may be withdrawn from a source of supply shown as a tank I6 by means of a' pump I1 and delivered to the mixer I3. The pumps II and Il are shownas being driven by a variable speed motor I8 with a variable speed device I9 between the motor and the pump Il so that proportioned streams of -oil and reagent may be delivered to 4the mixer I3, but any suitable mechanism for delivering proportioned streams maybe employed in lieu thereof.

The mixer I3 is preferably of the type dis.

closed in my'copending application Serial No. 190,673, filed February 15, 1938, in which a stream of the precipitating agent is injected at right angles into a flowing stream of the oil, but m-ay be any type of closed flow mixer such as a closed mechanical agitator. The precipitating agent employed precipitates materials other than phos phatides, particularly proteinaceous material, so that the same can be separated from the oil. The resulting mixture of oil and foots may be passed through a second heat exchanger 20 similar to the heat exchanger I2, and delivered to y The separator 2| is preferably of the type disclosed in Patent No. 2,100,277, granted November 23, 1937,

but may be of any type capable of continuously centrifugally separating the precipitated foots from the oil. The foots are discharged as the heavy eiiluent through a spout 22 into a receiver 23 and the oil is discharged as the light eilluent through a spout 2l into a tank 25. The tank 25 is preferably closed from the atmosphere and provided with a vent 26, although an open tank may be sometimes employed without damaging the oil.

The o'il from which certain of the impurities, particularly proteins, have been removed, is withdrawn from the tank llby a pump 23 and delivered through a heat exchange device 21 to a mixer 28. The phosphatide precipitating agent is withdrawn from the source of supply shown as a tank 23 by a lpump 30 and delivered to the mixer 23. The pumps 26 and 30 may be driven by a variable speed motor 3| with a variable speed device 32 between the motor and the pump 30, a1- though other types oi' proportioning mechanisms may be employed. The mixer 28 may be similar to the mixer I3 and on mixing the phosphatide precipitating agent with the oil phosphatides are precipitated and rendered separable from the oil. The resulting mixture may be passed through another heat exchange device 33 and delivered to a continuous centrifugal separator 34. The separator 34 may also be of the heated type referred to or may be any other type of centrifugal capable of continuously separating precipitated phosphatides from the oil. The phosphatides and excess precipitating reagent are discharged as the heavy eiiluent through a spout 35 into a receiver 36 and the oil is discharged as the light effluent through a spout 31 into a receiver 38.

The protein precipitating reagent may be any material which will selectively precipitate .proteins and other impurities from the oil Without precipitating substantial amounts ofphosphatides. It has been found that water alone, if quickly admixed with the oil in small quantities and then quickly separated therefrom, will pre cipitate and cause separation of proteinaceous and other impurities in the oil in preference to the phosphatides. However, improved results are accomplished by employing such protein precipitating reagents as alum or tannic acid in dilute solutions. These agents will likewise precipitate substantial amounts of phosphatides, unless the pH of the solution is adjusted to substantial neutrality by the addition of slight amounts of alkalies. Thus, solutions having a -pH between 6 and 7 can be employed to precipitate substantially all of the proteins without precipitating substantial amounts ofphosphatides. 'I'he alkali employed may be caustic soda or sodium carbonate, although substantially any alkali may be employed in small amounts. As long `as small amounts of water or substantially neutral solutions of protein precipitating materials are employed, and the separation is made promptly after mixing, the phosphatides are largely retained in the oil.

The phosphatides may then be precipitated by adding a solution which is slightly acidic. The isoelectric .points of the phosphatides vary over a considerable range, but will usually fall between a pH of from 2 to 6. For oils containing phosphatides having an isoelectric point of approximately pH 6, the protein precipitating agent should have a pH of very close to 7 to prevent separation of substantial amounts of phosphatides with the iproteinaceous material. It is preferred to employ edible organic acids as the phosphatide precipitating agents, for example, acetic acid, citric acid, tartaric acid, lactic acid, etc. These acids are employed in aqueous solution sufcient to give a hydrogen ion concentration approaching the isoelectric point of the phosphatides of the particular oil being-treated. Boric acid is an especially suitable agen't, as this material also preserves the phosphatides against putrefaction or decompositioneven if allowed to stand in a moist condition. Otherwise, the phosphatidic material can be preserved by drying the same or by further purication treatments such as washing with acetone in order to remove decomposable impurities in the phosphatides. Although edible organic acids are preferred, it is possible to employ dilute solutions of mineral acids such as hydrochloric or sulfuric acid or acidic salts. Also suitable buil'er salts may be employed with any of the acids to maintain the desired hydrogen ion concentration. Any precipitating agent employed may be later washed from the phosphatides, ii' necessary or desirable to produce an edible product.

The heat exchanger l2 may .be employed to bring the crude oil to a desired temperature for mixing. This temperature will vary with diilerent oils being treated and the amount of gums present therein. Such temperatures will vary over a wide range, for example, from 70 F. or below up to approximately 160 F. The heat exchanger 20 is employed to bring the mixture to the most eifective temperature for separation of the precipitated impurities from the oil and this temperature will ordinarily range between and F., depending upon the oil being treated. If the temperature of mixing giving most eiiicient precipitation is found to be low, the heat exchanger I2 may be omitted and all of the heat necessary for separation imparted to the mixture in the heat exchanger 2U. However, it is lusually necessary to separate the precipitated material from the oil substantially immediately after mixing in order to prevent substantial amounts of phosphatides being precipitated and separated. It is, therefore, usually desirable to supply the heat necessary for separation by the heat exchanger l2 and eliminate the heat exchanger 20, although the heat exchanger 20 maybe employed with certain oils to give a short time of contact between the oil and reagent prior to separation, irrespective of whether the mixture being passed therethrough is heated or cooled. By properly correlating the temperature -of mixing, the time of treatment and the temperature of separation, and employing a substantially neutral precipitating agent, a major amount of the impurities in the oil other than phosphatides can .be separated from the oil without separating substantial amounts of phosphatides therewith.

The heat exchangers 21 and 33 are employed in the phosphatide'precipitating step for purposes analogous to those of the heat exchangers I2 and 20; that is to say, lthe heat exchanger 21 may be employed to heat or cool the oil to bring the same to the mixing temperature found most eilicient for precipitating the phosphatides in the particular oil being treated and the heat eX- changer 33 may vbe employed to give a desired time of treatment of the mixture prior to separation and also to adjust the temperature to the desired point for separation. The temperature of mixing will likewise vary between wide limits, for example 70 F. to 160 F., depending upon the particular oil .being treated, and the temperature of* separation may vary between 100 F. and 160 F.A By correlating the temperature of mixing, the time between mixing and separation and the temperature of separation, substantially complete separation of relatively pure phosphatides can be effected. As all of these factors will vary with the type of oil being processed and the amount of phosphatides contained therein, no precise gures can be given.v

The amounts of protein precipitating agent and phosphatide precipitating agent will likewise vary with the oil being treated. Thus, in both cases the amounts of these agents will usually be below 5% of the oil and may nin as low as 1/r% to 1%.

' Excess amounts of reagent are to be avoided, as a certain amount of oil will be entrained in the separated proteins' and also in the separated phospha-tides and the amount of this oil will increase with the amount of material separated. As the agents are also separated with the proteins and phosphatides, excess agents will cause increased amounts of neutral oil to be entrained. The crude oil being treated ordinarily also contains free fatty acids and the oil discharged from the process into the receiver 38 will still contain free fatty acids, although the acidity ofthe oil is usually reduced, as acidic material other than free fatty acids is precipitated with the materials separated from the oil, particularly with the proteins. The oil discharged from the process may then be subjected to further refining steps such as alkali refining steps to produce a completely refined oil.

While the continuous process above described more etliciently separates the proteins and phosphatides from the oil and results in less entrainment of the oil in these'material-s, it is possible to carry on either` the protein separation step or the phosphatide separating step, or both, as batch or semi-batch operations. Thus, in either case, the precipitating agent may -be mixed with a, body of the oil in a vessel provided with an agitator and the resulting mixture withdrawn as a stream from the vessel during agitation and delivered to a continuous centrifugal separator.

. Also, the oil and precipitating agent may be continuously mixed and then delivered to a settling vessel wherein the proteins or the phosphatides are settled from the oil. Likewise, batch mixing followed by a batch settling step may be performed in the same or different vessels. Such batch or semi-batch processes, particularly batch settling steps, result in a less effective separation between the proteins and the phosphatides and also result in a materially larger amount of oil being entrained in the separated materials; that is to say, some measure of success may be attained in batch operations, but the continuous operation described produces purer phosphatides and less losses of neutral oil.

While I have described the preferred embodiment of my invention, it is understood that the details thereof may be varied within the scope of the following claims.

I claim:

1. 'I'he process of recovering relatively pure phosphatides from vegetable oils containing vgummy materials including phosphatides, which comprises, admixing a small amount of an aqueous medium having a pH of approximately 7 with said oil to precipitate gummy materials other than phosphatides, separating the precipitated vcentritugally separating said precipitated phos- 'approximately 2 and 6 to precipitate relatively pure phosphatides and separating said precipitated phosphatides from said oil.

2. The process of recovering re.atively pure phosphatides from vegetable oils containing gummy materials including phosphatides, which comprises, admixing a small amount oi' an aqueous medium having a pH of pproximately rI and containing a protein precipitating agent with said oil to precipitate gummy materials other than phosphatides, separating the precipitated niaterial from said oil, thereafter mixing with said oil an aqueous medium having a pH between approximately 2 and 6 to precipitate relatively pure phosphatides and separating said precipitated phosphatides trom said oil.

3. The processor' recovering relatively pure phosphatides from vegetable oils containing gummy materials including phosphatides, which comprises, admixing a small amount of an aqueous medium having a pH of approximately 7 with said oil to precipitate guirimy materials other than phosphatides, separating the precipitated material from said oil, thereafter mixing with said yoil an aqueous solution containing an organic acid and having a pH between approximately a and 6 to precipitate relatively pure phosphatides and seperating said precipitated phosphatides from said oil.

4. The processof ,recovering relatively pur phosphatides from vegetable oils containing gummy materials including phosphatides, which comprises, admixing a small amount of an aqueons medium having a pH of approximately 7 wi-th said oil to precipitate gummy materials other than phosphatides, separating the precipitated material from said oil, thereafter mixing with said oil an aqueous solution containing an edible organic acid and having a pHbetween approximately 2 and 6 to precipitate relatively pure phosphatides and separating said 'precipitated phosphatides from said oil.

5. The process of recovering relatively pure phosphatides from vegetable oils containing gummy materials including phosphatides, which comprises. continuously mixing a stream of said oil with a stream of aqueous medium having a DH of approximately 7 in an amount sulcient to precipitate a substantial amount of said phosphatides, promptly delivering the resulting mixture to a continuous centrifugal separator and separating the precipitated material from said oil, thereafter mixing a stream of said separated oil with a stream of an aqueous medium having a pH between approximately 2 and 6 to precipitate relatively pure phosphatidesand continuously phatides from said oil.